DE102007017875B4 - Fan cover and drive - Google Patents

Abstract

fan cover
characterized in that
Slots for reducing the noise emission are arranged on the circumference of the fan cowling,
the slots being arranged in such a way that they hinder the propagation of coupled-in vibration components, in particular in the connection region of coupled-in vibration components,
wherein at the periphery of the connecting portions with the motor housing at an angle of α = 360 ° / n to each other,
wherein a respectively arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region, applies to the applies 0 ≤ β ≤ α / 2,
wherein another, each in the circumferential direction after the connection region arranged slot 1 has an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2,
with the number of slots being 2n.

Description

The invention relates to a fan cover and a drive.

From the US 5,118,252 A. a fan cowl is known, the reduced operating noise achievable by stiffening areas (see column 4, line 21 and claims 9 to 10 of this document). The production of the fan guard is very expensive, except as a plastic injection molded part.

From the US Pat. No. 6,896,095 B2 is a fan cover known to be reduced by the flow noise by means of recesses.

From the JP S62-217 833 A an electric motor is known which has a fan. In this case, a fan guard is provided, the resonance boxes, presumably Helmholtz resonators, comprises, for the absorption of vibrations of certain frequencies.

The invention is therefore based on the object to improve the safety and environmental protection, in particular, the emissions are to be reduced in industrial drives.

According to the invention, the object is achieved in the fan guard according to the in claim 1, 2 or 3 and in the drive according to the features indicated in claim 17.

Important features of the invention are that slits for reducing the noise emission are arranged on the circumference of the fan cowl on the fan cowl, wherein the slots are arranged such that they hinder the propagation of coupled-in vibration components, in particular in the connection region of coupled-in vibration components.

According to the invention, the connecting regions, in particular screw connections, with the motor housing at the periphery at an angle of α = 360 ° / n to each other. The advantage here is that in the invention any number of attachment points on the circumference is providable.

According to the invention, a slot arranged in each case in the circumferential direction in front of the connection region has an angle β to the connection region, for which the following applies 0 ≤ β ≤ α / 2, especially α / 20 ≤ β ≤ α / 5. Likewise, a respective slot arranged in the circumferential direction after the connecting region has 1 an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2, especially α / 20 ≤ γ ≤ α / 5. The advantage here is that a particularly good reduction of the airborne sound emissions can be achieved, especially in electric motors with a power between 0.3 kw and 500 kW and at a speed between 0 and 5000 revolutions per minute.

Alternatively, the important features according to claim 2, that the fan cover connection areas for attachment of the fan cover to a structure-borne sound component comprises, wherein slots are provided for reducing the airborne radiation introduced via the connection regions from the coupled regions.

In a further alternative, the important features according to claim 3, that the fan cover connecting areas for attachment of the fan cover to a structure-borne sound component comprises, wherein slots are provided as a sound brake for coupled via the connection areas structure-borne sound.

The fan guard is exemplified for industrial drives, which usually include transmissions driven by electric motors, with the electric motors supplied by converters. Pulse width modulated operation of the inverter and other electrical variables lead to time-varying forces on parts of the drive. For example, vibrations are excited by electromagnetically influenced parts. These vibrations cause the emission of sound as an emission into the environment. In particular, vibrations are also transmitted from the motor housing, including bearing flange, via screw connections to the fan hood of the motor screwed to the motor housing, where it is emitted as sound.

The advantage here is that with very cost-effective means the noise emissions are reducible and thus improves environmental protection. In addition, the mass of the arrangement, so the drive is reduced, and thus reduces the weight. In addition, material is saving and thus the environmental protection can be improved. It is therefore important in the invention that structure-borne noise is indeed coupled into the fan cover at the attachment points, but by means of the slots as a sound brake or structure-borne noise obstacle the propagation of structure-borne noise into other areas of the fan cover can be reduced or at least reduced. Thus, even sheet metal can be selected as a material for the fan cover and still the conversion of structure-borne noise in airborne noise can be reduced, which would be very pronounced without the slots. The slots are thus arranged in the area around the fastening means in such a way that they impede the propagation of structure-borne noise. It is also important that the structure-borne sound vibrates in different modes, that is, has vibration modes in the radial, axial direction and the like. The invention teaches that the slots are mounted so that those Modes that make up the main part of the coupled structure-borne noise are reduced or even suppressed by the shape and the shape of the slots.

Distinguishing from the sound forms mentioned here are the flow noise and the associated acoustic emission, which are caused by the rotating fan blade and the resulting air currents. The invention does not relate to these sound emissions. The invention mentioned in the fan hood coupled body sound is generated by the device to which the fan guard is attached. For example, this is a drive whose electric motor is powered by a converter. On the one hand, vibrations can thus be coupled in by the converter; on the other hand, oscillations can also be coupled in by the alternating current supply to the stator windings. In addition, vibrations also originate from the gearbox or bearings and not fully balanced components. Also other causes are present. In this way, structure-borne noise is generated, which occurs on the housing part of the drive, in particular a bearing plate of the electric motor of the drive. By means of the attachment areas Einkoppelungsmöglichkeiten be created for this structure-borne noise in the fan guard. Since the fan cowl is designed around the engine essentially round or as a rounded polygon. Likewise, the motor is designed to be substantially round to the fan guard, with cooling fins and the like are not taken into account. Therefore, a substantial portion of the coupled structure-borne noise propagates in the circumferential direction and another important component also propagates in the axial direction. Accordingly, the slots are designed such that this propagation is reducible or even preventable.

Preferably, as a material for the fan cowl, a sheet metal, in particular steel sheet selectable. Thus, the slots are easily and quickly generated by punching. In addition, a high resistance to mechanical loads can be achieved, in particular in contrast to the use of plastic.

In an advantageous embodiment would omit the slots, the essential portion of the coupled vibration components in the circumferential direction and / or propagate in the axial direction. The advantage here is that the slots are formed so that the spread of these essential components can be prevented or reduced.

In an advantageous embodiment, the slots are oriented in the axial and / or circumferential direction. If the slots are oriented in the axial direction, it is advantageous to reduce the oscillation amplitudes of radial modes which would also propagate in the circumferential direction starting from the coupling-in areas. When oriented in the circumferential direction advantageously according to vibration amplitudes of other modes can be reduced. In particular, both types of slit can be combined.

In an advantageous embodiment, the slots arcuate, U-shaped and / or C-shaped surround the Einkoppelungsbereiche. In particular, the opening of the arc, the U or the C is oriented in the anal direction. The advantage here is that the propagation of appropriate modes in the fan guard can be suppressed or at least reduced.

In an advantageous embodiment, the coupling-in areas comprise connecting areas, in particular screwed connections, with the motor housing, in particular with a bearing plate of the motor housing. The advantage here is that conventional connection means can be used, via the structure-borne sound is coupled. So no sound-absorbing connection means, such as plastic washers and plastic screws must be used. When using such means, of course, even better reductions in the noise emissions can be achieved.

In an advantageous embodiment, the fan cowl comprises a cylindrical region in a first axial section, a bevelled region in a second axial region, and a fan cowl lattice in a third axial region. The advantage here is that more sound-reducing slots are providable. These are also inexpensive to produce.

In an advantageous embodiment, the slots extend in the axial direction only partially over the width of the cylindrical portion. The advantage here is that the stability of the fan guard is only slightly affected. In particular, extend from the edge or are provided only inside the fan guard.

In an advantageous embodiment, the axial extent t of the slots is 0.5 · c ≦ t ≦ 5 · c, where c is the distance from the center of the connection region to the hood edge of the fan cover. The advantage here is that thus in the electric motors with a power between 0.3 kw and 500 kW and at a speed between 0 and 5000 revolutions per minute a particularly good reduction of airborne noise emissions can be achieved.

In an advantageous embodiment, angle γ and angle β are equal in magnitude. The advantage here is that a simple production is achievable and a particularly good reduction of airborne emissions can be achieved.

In an advantageous embodiment, the respective slots arranged in the circumferential direction after and in front of the connection region are arranged symmetrically with respect to the connection region. The advantage here is that

In an advantageous embodiment, the arrangement and formation of the slots are designed such that the sound emissions are reduced. The advantage here is that the molding no cost increases and thus a cost-effective method for reducing emissions is provided.

In an advantageous embodiment, the slots are arranged on the circumference of the fan cover between mounting screws, in particular around them. The advantage here is that occurring there large vibration amplitudes of rotating waves and standing waves can be reduced.

In an advantageous embodiment, the fan cowl performs a housing-forming function for a fan and / or an angle sensor connected to the motor shaft. The advantage here is that the fan cover is a housing part that radiates low sound emission in a cost effective manner.

Important features of the invention in the drive are that it comprises at least one electric motor and / or a transmission, wherein slots are arranged on at least one housing part for reducing the noise emission. For example, the housing part is a cooling fin, a connection box or a fan cover. Particularly flat or thin flat parts, such as ribs and hoods contribute without the slots considerable amounts of sound emission.

The advantage here is that the drive by simple and inexpensive measures, such as slots of parts, sound-reducing executable. In any case, the structure-borne noise generated by the engine and / or transmission, which is coupled into the housing part at the respective attachment areas and / or connection areas for connection to the engine and / or transmission, in its propagation within the housing part preventable or at least is the spread erschwerbar. Thus, then occurs in the housing part only little structure-borne sound and it is then produced and radiated as a result, only little airborne sound. From this invention-related airborne sound that airborne sound is to be distinguished, which is generated by air currents on the fan blades and / or recesses of the fan cowl.

In an advantageous embodiment, a housing part is a cooling fin, a connection box or a fan cover. The advantage here is that the slots in various components are providable, not necessarily a sheet metal part but also a casting is used.

In an advantageous embodiment, connecting regions, in particular comprising fastening screws, which can be screwed into threaded bores of the motor housing, are provided for connecting the fan cowl to the motor housing, in particular, structure-borne noise from the motor housing via the connecting regions into the fan cowl. The advantage here is that, although structure-borne noise may be coupled in via the connection region, simple means, such as slots, are then used to reduce the propagation of structure-borne noise into the housing part. Thus, less airborne sound produced by the structure-borne sound can then also be emitted from this housing part, in particular the fan cowl.

In an advantageous embodiment, slots are arranged in areas of the fan guard with low rigidity or strength. The advantage here is that exactly in these areas without the slots large amplitudes would occur. The fact that the slots are made small, so short, then the strength is only slightly reduced, but reduces the vibration ability, in particular, the formation and spreading of circumferential and pulsating waves is prevented by the slots.

In an advantageous embodiment, slots are arranged in the second or third axial region of the fan cowl. The advantage here is that corresponding vibrations can be suppressed or at least reduced.

Further advantages emerge from the subclaims.

LIST OF REFERENCE NUMBERS

1

slot

2

Recess for fixing screws

3

fan cover

4

Fan cover grid

5

cylindrical area

6

bevelled area

30

fixing screw

31

Lagerflansch

40

U-shaped or C-shaped slot

The invention will now be explained in more detail with reference to figures:

In the 1 is a fan cover according to the invention for the drive.

The fan cover 3 is by means of fastening screws, which are at the recesses 2 are provided, connected to the motor housing of the drive. There are four recesses 2 provided at the periphery.

The fan cover 3 has a fan cowl grille 4 on, which is provided for passing the cooling air flow of the fan, which of the fan cover 3 is provided to protect and influence the cooling air flow. In this case, the fan is mounted on an axial end portion of the engine, preferably a bearing flange. The cylindrical area 5 is arranged axially oriented. The beveled area 6 joins this area 5 on and ends in the area of the fan cowl grille 4 ,

On the circumference of the fan cover 3 There are eight slots 1 provided, which are oriented in the axial direction. Preferably, two are each close to the respective recess 2 intended.

In further embodiments of the invention are eight or a different number of recesses 2 intended. The number of slots and the shape, in particular length, of the slots are adaptable and adaptable to reduce the noise emissions.

Other embodiments of the invention are also other orientations of the slots 1 advantageous, such as radial or oblique arrangement of the slots. The slots can therefore also be provided in the slanted area or even in the fan cowl lattice. It is particularly advantageous to mount the slots in areas where, without the slots, a large or even a locally maximum oscillation amplitude occurs.

The motor housing is coupled via the fastening screws in the area of the recesses 2 Structure-borne noise. With axial orientation of the slots 1 next to the recesses 2 is a propagation of the coupled structure-borne sound prevented in the circumferential direction or at least reduced. It is, so to speak, the vibration wave propagation in the circumferential direction interrupted. Through the slots, the vibration amplitudes and thus the sound radiation, so also noise of the drive, greatly reduced. It is also important that there is a low tension in the material in the circumferential direction in those areas in which no fastening screws are provided between the slots. Thus, similar to an unstrung string of a stringed instrument, no or only little structure-borne noise can be converted into airborne sound and radiated. As material for the fan cover 3 Thus, metal is also selectable, which offers better protection than plastic, but radiates a high proportion of structure-borne noise as airborne sound when tightened attachment. By means of the slots but the essential 1 area is relaxed and thus reduces the radiation or even prevented.

Of course, other housing areas, such as motor housing, cooling fins of the motor housing, terminal box on the motor housing and the like, also emit sound. Again, attaching slots in areas of least rigidity is beneficial and reduces emissions.

If the structure-borne noise coupled in by the motor housing has a significant proportion of vibrations which are pronounced in the axial direction instead of as described above in the circumferential direction, it is preferably provided in the slot in the circumferential direction axially behind the fastening screw.

In 4 a combination of two axial slots and a slot is shown in the circumferential direction, in which the slots are summarized as a U-shaped or C-shaped slot 40 inside the sheet metal material of the fan cowl. Thus, propagation and vibrations of structure-borne noise are reduced in the circumferential direction and completely prevented in the axial direction. Only about the two narrow webs in the circumferential direction is still transmitted some structure-borne noise. However, the narrow webs have the advantage that even when tightening the mounting screws no significant deformation of the axial region of the fan cover takes place, in which it is provided on the bearing plate and / or motor housing. Even if so cooling fins or other ripples are provided on the motor housing, a possible only small and small deformation is reached when tightening the mounting screws, so that the contact protection is maintained. In particular, no defined according to standard finger between the fan guard and bearing flange or motor housing into the interior of the engine can be inserted. The security is thus increased.

In 3b is illustratively shown how the fan cover 3 deformed when the mounting screws in the bearing plate 31 of the motor are screwed in and no slots are present. In the case of large motors, the deformation can be so great that safety is jeopardized because a finger between the end shield and the fan cowl can be inserted into the interior of the engine, even though it was not insertable before tightening the screws. During operation of the motor, the effect of the vibration-induced movement of the fan cowling is additionally added.

In 3a is shown that in the presence of the slots according to the invention, the fan guard 3 not deformed or at least not visibly deformed but essentially remains in its cylindrical shape when the mounting screws in the bearing plate 31 be screwed in the engine.

In the 2 is still shown how an optimal dimensioning of the slots is provided for an industrial electric motor. The information refers to the axial slots 1 to 1 , each one being left beside the fixing screw 30 provided slot 1 has an angle β to the mounting screw and the right next to the mounting screw 30 provided slot 1 has an angle γ to the fastening screw. For n equally spaced mounting screws, the angle between these screws is α = 360 ° / n. Thus, it is possible: 0 ≦ β ≦ α / 2, 0 ≦ γ ≦ α / 2. However, it has turned out that at: α / 20 ≦ β ≦ α / 5, α / 20 ≦ γ ≦ α / 5 very good reduction of sound radiation can be achieved. In addition, the axial extent t of the slots is preferably such that 0.5 × c ≦ t ≦ 5 × c, where c is the distance from the screw axis to the hood edge of the fan cover 3 is.

It is not necessary that the angle γ and the angle β are equal in magnitude, but a symmetrical arrangement within the scope of the manufacturing tolerances is advantageous.

For the U- or C-shaped slots after 4 The same applies, wherein the U or C consists essentially of the two axially aligned slots 1 to which the said relationships apply, and a connecting slot, which is oriented in the circumferential direction by way of example.

Preferably, the fan cover 3 By bayonet lock with the bearing flange or motor housing connectable, for which purpose the fastening screws are screwed into the bearing flange or motor housing. For this purpose, the recesses for fastening screws are shaped accordingly. In this way, the fan cover is fast and easy connectable.

The sheet of fan cover is preferably selected as a steel sheet. Instead of four screws on the circumference, three have proven to be particularly advantageous. It is also important in the invention that the distortion caused by the mounting by means of the fastening screws of the fan cover is reduced by the slots, wherein the slots are mounted on both sides of the respective screw connections. The reduction of the strain then causes a reduction of the airborne sound radiation from the relaxed areas out.

In advantageous embodiments, the fan cowling is at least towards the engine, ie axial region in which the connection regions are arranged, substantially round or designed as a rounded polygon. Depending on the type of execution although different high natural frequencies can be generated and thus different degrees of propagation effected, but the underlying principle of the invention is similar operating principle. In this case, the radial vibration components coupled in by the engine preferably extend in the circumferential direction starting from the connecting regions. Vibration components coupled in by the transmission also propagate in the axial direction starting from the connection regions. Accordingly, the slots are arranged as a sound barrier, in particular each oriented transversely to the propagation directions. Several slots can also be connected to each other.

Claims (17)

Fan shroud, characterized in that slots for reducing the noise emission are arranged on the circumference of the fan cowl, wherein the slots are arranged such that they are the propagation of coupled vibration components, in particular in the connection region coupled-vibration components obstructive, at the periphery of the connecting portions with the motor housing at an angle from α = 360 ° / n have to each other, wherein each arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region for which applies 0 ≤ β ≤ α / 2, wherein another, each arranged in the circumferential direction after the connection region slot 1 has an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2, with the number of slots being 2n. Fan cover, comprising connecting portions for attaching the fan cover to a structure-borne sound component, wherein slots are provided to reduce the coupled via the connection areas structure-borne sound airborne radiation, wherein at the periphery of the connecting portions with the motor housing at an angle of α = 360 ° / n have to each other, wherein each arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region for which applies 0 ≤ β ≤ α / 2, wherein one in each case arranged in the circumferential direction after the connection region slot 1 has an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2, with the number of slots being 2n. Fan cover, comprising connecting portions for fastening the fan cover to a structure-borne sound component, wherein slots are provided as a sound brake for coupled via the connection areas structure-borne sound, wherein at the periphery of the connecting portions with the motor housing at an angle of α = 360 ° / n have to each other, wherein each arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region for which applies 0 ≤ β ≤ α / 2, wherein one in each case arranged in the circumferential direction after the connection region slot 1 has an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2, with the number of slots being 2n. Fan cover according to one of the preceding claims, characterized in that the slots are oriented in the axial and / or circumferential direction. Fan shroud according to one of the preceding claims, characterized in that the slots arcuate, U-shaped and / or C-shaped surrounding the Einkoppelungsbereiche, in particular wherein the opening of the arc, the U or C is oriented in the axial direction. Fan cover according to one of the preceding claims, characterized in that the coupling-in areas connecting areas, in particular screw, with the motor housing, in particular with a bearing plate of the motor housing include. Fan shroud according to one of the preceding claims, characterized in that the fan shroud comprises a cylindrical portion in a first axial portion, a beveled portion in a second axial region and a fan cowl lattice in a third axial region. Fan cover according to one of the preceding claims, characterized in that the slots extend in the axial direction only partially over the width of the cylindrical region, in particular extend from the edge or are provided only in the interior of the fan cover. Fan cover according to one of the preceding claims, characterized in that the connecting regions are screw connections. Fan cover according to one of the preceding claims, characterized in that each arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region for which applies α / 20 ≤ β ≤ α / 5. Fan cover according to one of the preceding claims, characterized in that each arranged in the circumferential direction after the connection region slot 1 has an angle γ to the connection region for which applies α / 20 ≤ γ ≤ α / 5. Fan cover according to one of the preceding claims, characterized in that for the axial extent t of the slots 0.5 · c ≤ t ≤ 5 · c applies, where c is the distance from the center of the connection region to the hood edge of the fan cover 3 is. Fan cover according to one of the preceding claims, characterized in that angle γ and angle β is equal in magnitude. Fan cowl according to one of the preceding claims, characterized in that the respective slots arranged in the circumferential direction to and before the connection region are arranged symmetrically to the connection region. Fan cover according to one of the preceding claims, characterized in that the arrangement and formation of the slots are designed such that the noise emissions are reduced. Fan shroud according to one of the preceding claims, characterized in that the fan shroud performs housing-forming function for a fan and / or connected to the motor shaft angle sensor. Drive, comprising at least one electric motor and / or a transmission, characterized in that slots are arranged on at least one housing part for reducing the sound emission caused by structure-borne noise emitted to the ambient air, wherein a housing part is a cooling fin, a connection box or a fan cowl, wherein the Extend the connection areas with the motor housing at an angle of α = 360 ° / n have to each other, wherein each arranged in the circumferential direction in front of the connecting portion slot 1 has an angle β to the connection region for which applies 0 ≤ β ≤ α / 2, wherein one in each case arranged in the circumferential direction after the connection region slot 1 has an angle γ to the connection region for which applies 0 ≤ γ ≤ α / 2.

Images